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Hepprich M, Ebrahimi F, Christ E. Dyslipidaemia and growth hormone deficiency - A comprehensive review. Best Pract Res Clin Endocrinol Metab 2023; 37:101821. [PMID: 37821339 DOI: 10.1016/j.beem.2023.101821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Growth hormone deficiency (GHD) is a common complication of several pituitary and hypothalamic disorders and dependent on the onset of disease. It may have severe clinical implications ranging from growth retardation in childhood-onset, to impaired lipid metabolism and increased cardiovascular risk and mortality in adults. GH effectively modulates lipid metabolism at multiple levels and GHD has been associated with an atherogenic lipid profile, that can be reversed by GH replacement therapy. Despite increasing knowledge on the effects of GH on several key enzymes regulating lipid metabolism and recent breakthroughs in the development and wider availability of recombinant GH preparations, several questions remain regarding the replacement therapy in adults with GHD. This review aims to comprehensively summarize the current knowledge on (i) lipid profile abnormalities in individuals with GHD, (ii) proposed mechanisms of action of GH on lipid and lipoprotein metabolism, and (iii) clinical implications of GH replacement therapy in individuals diagnosed with GHD.
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Affiliation(s)
- Matthias Hepprich
- Department of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland; Metabolic Centre, Cantonal Hospital Olten, Olten, Switzerland
| | - Fahim Ebrahimi
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Department of Gastroenterology and Hepatology, Clarunis University Center for Gastrointestinal and Liver Diseases, Basel, Switzerland
| | - Emanuel Christ
- Department of Endocrinology, Diabetes and Metabolism, University Hospital Basel, Basel, Switzerland.
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2
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Ginting RP, Lee JM, Lee MW. The Influence of Ambient Temperature on Adipose Tissue Homeostasis, Metabolic Diseases and Cancers. Cells 2023; 12:cells12060881. [PMID: 36980222 PMCID: PMC10047443 DOI: 10.3390/cells12060881] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/10/2023] [Accepted: 03/10/2023] [Indexed: 03/14/2023] Open
Abstract
Adipose tissue is a recognized energy storage organ during excessive energy intake and an endocrine and thermoregulator, which interacts with other tissues to regulate systemic metabolism. Adipose tissue dysfunction is observed in most obese mouse models and humans. However, most studies using mouse models were conducted at room temperature (RT), where mice were chronically exposed to mild cold. In this condition, energy use is prioritized for thermogenesis to maintain body temperature in mice. It also leads to the activation of the sympathetic nervous system, followed by the activation of β-adrenergic signaling. As humans live primarily in their thermoneutral (TN) zone, RT housing for mice limits the interpretation of disease studies from mouse models to humans. Therefore, housing mice in their TN zone (~28–30 °C) can be considered to mimic humans physiologically. However, factors such as temperature ranges and TN pre-acclimatization periods should be examined to obtain reliable results. In this review, we discuss how adipose tissue responds to housing temperature and the outcomes of the TN zone in metabolic disease studies. This review highlights the critical role of TN housing in mouse models for studying adipose tissue function and human metabolic diseases.
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Affiliation(s)
- Rehna Paula Ginting
- Department of Integrated Biomedical Science, Soonchunhyang University, Cheonan 31151, Republic of Korea
| | - Ji-Min Lee
- Soonchunhyang Institute of Medi-Bio Science (SIMS), Soonchunhyang University, Cheonan 31151, Republic of Korea
| | - Min-Woo Lee
- Department of Integrated Biomedical Science, Soonchunhyang University, Cheonan 31151, Republic of Korea
- Soonchunhyang Institute of Medi-Bio Science (SIMS), Soonchunhyang University, Cheonan 31151, Republic of Korea
- Correspondence: ; Tel.: +82-41-413-5029
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Apolipoprotein B and Cardiovascular Disease: Biomarker and Potential Therapeutic Target. Metabolites 2021; 11:metabo11100690. [PMID: 34677405 PMCID: PMC8540246 DOI: 10.3390/metabo11100690] [Citation(s) in RCA: 84] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/04/2021] [Accepted: 10/06/2021] [Indexed: 12/19/2022] Open
Abstract
Apolipoprotein (apo) B, the critical structural protein of the atherogenic lipoproteins, has two major isoforms: apoB48 and apoB100. ApoB48 is found in chylomicrons and chylomicron remnants with one apoB48 molecule per chylomicron particle. Similarly, a single apoB100 molecule is contained per particle of very-low-density lipoprotein (VLDL), intermediate density lipoprotein, LDL and lipoprotein(a). This unique one apoB per particle ratio makes plasma apoB concentration a direct measure of the number of circulating atherogenic lipoproteins. ApoB levels indicate the atherogenic particle concentration independent of the particle cholesterol content, which is variable. While LDL, the major cholesterol-carrying serum lipoprotein, is the primary therapeutic target for management and prevention of atherosclerotic cardiovascular disease, there is strong evidence that apoB is a more accurate indicator of cardiovascular risk than either total cholesterol or LDL cholesterol. This review examines multiple aspects of apoB structure and function, with a focus on the controversy over use of apoB as a therapeutic target in clinical practice. Ongoing coronary artery disease residual risk, despite lipid-lowering treatment, has left patients and clinicians with unsatisfactory options for monitoring cardiovascular health. At the present time, the substitution of apoB for LDL-C in cardiovascular disease prevention guidelines has been deemed unjustified, but discussions continue.
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McFie PJ, Chumala P, Katselis GS, Stone SJ. DGAT2 stability is increased in response to DGAT1 inhibition in gene edited HepG2 cells. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158991. [PMID: 34116261 DOI: 10.1016/j.bbalip.2021.158991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 05/21/2021] [Accepted: 06/05/2021] [Indexed: 12/14/2022]
Abstract
In eukaryotic organisms, two unrelated acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes, DGAT1 and DGAT2, catalyze the final step of the triacylglycerol biosynthetic pathway. Both enzymes are highly expressed in lipogenic tissues, such as adipose tissue, small intestine and the liver. DGAT2 has a prominent role in hepatocyte lipid metabolism synthesizing triacylglycerols that are utilized for very low-density lipoprotein assembly. However, due to the lack of useful antibodies to detect endogenous DGAT2 protein, it has been difficult to determine how this enzyme functions at the cellular level. We have unsuccessfully tested many commercial antibodies as well as our own "in-house" antibodies. There is currently no evidence that DGAT2 undergoes processing such that antigenic epitopes to these antibodies are removed. As an alternative, many studies have utilized epitope tagged versions of DGAT2 overexpressed in cells. These approaches can provide valuable information about a protein, but can be subject to artifacts, such as mislocalization, misregulation, protein aggregation and abnormal protein-protein interactions. In this study, we used gene editing with CRISPR/Cas9 to add three consecutive FLAG epitopes to the C-terminus of endogenous DGAT2 in HepG2 cells. HepG2 cells, derived from a human hepatocellular carcinoma, have been routinely used as a cell model to study human hepatocyte lipid and lipoprotein metabolism. Using this system allowed us to successfully detect DGAT2 expressed from its endogenous locus in HepG2 cells by immunoblotting with anti-FLAG antibodies.
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Affiliation(s)
- Pamela J McFie
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Paulos Chumala
- Department of Medicine and the Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, Saskatoon, Saskatchewan S7N 2Z4, Canada
| | - George S Katselis
- Department of Medicine and the Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, Saskatoon, Saskatchewan S7N 2Z4, Canada
| | - Scot J Stone
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
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Abstract
PURPOSE OF REVIEW Cardiovascular (CV) disease is a major cause of mortality in type 2 diabetes mellitus (T2D). Dyslipidemia is prevalent in children with T2D and is a known risk factor for CVD. In this review, we critically examine the epidemiology, pathophysiology, and recommendations for dyslipidemia management in pediatric T2D. RECENT FINDINGS Dyslipidemia is multifactorial and related to poor glycemic control, insulin resistance, inflammation, and genetic susceptibility. Current guidelines recommend lipid screening after achieving glycemic control and annually thereafter. The desired lipid goals are low-density lipoprotein cholesterol (LDL-C) < 100 mg/dL, high-density lipoprotein cholesterol (HDL-C) > 35 mg/dL, and triglycerides (TG) < 150 mg/dL. If LDL-C remains > 130 mg/dL after 6 months, statins are recommended with a treatment goal of < 100 mg/dL. If fasting TG are > 400 mg/dL or non-fasting TG are > 1000 mg/dL, fibrates are recommended. Although abnormal levels of atherogenic TG-rich lipoproteins, apolipoprotein B, and non-HDL-C are commonly present in pediatric T2D, their measurement is not currently considered in risk assessment or management.
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Affiliation(s)
- Bhuvana Sunil
- Department of Pediatrics, Division of Endocrinology and Diabetes, University of Alabama at Birmingham, CPPII M30, 1601 4th Ave S, Birmingham, AL, 35233, USA
| | - Ambika P Ashraf
- Department of Pediatrics, Division of Endocrinology and Diabetes, University of Alabama at Birmingham, CPPII M30, 1601 4th Ave S, Birmingham, AL, 35233, USA.
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Zhang J, Jazii FR, Haghighi MM, Alvares D, Liu L, Khosraviani N, Adeli K. miR-130b is a potent stimulator of hepatic very-low-density lipoprotein assembly and secretion via marked induction of microsomal triglyceride transfer protein. Am J Physiol Endocrinol Metab 2020; 318:E262-E275. [PMID: 31821038 DOI: 10.1152/ajpendo.00276.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
miR-130b is a microRNA whose expression is particularly elevated within adipose tissue and in the circulation in diabetic states. Hepatic miR-130b expression has been linked to hepatocellular carcinoma and changes in lipid metabolism. Here, we investigated the role of miR-130b in hepatic lipid homeostasis and lipoprotein export. We observed that overexpression of miR-130b-3p or -5p in HepG2 cells markedly enhanced the secretion of very-low-density lipoprotein (VLDL) particles, enhanced the secretion of [3H]glycerol metabolically labeled triglyceride (TG), and significantly increased the number or the average size of lipid droplets (LDs), respectively. Overexpression of miR-130b also altered the expression of key genes involved in lipid metabolism and in particular markedly increased both mRNA and protein expression levels of microsomal triglyceride transfer protein (MTP). Conversely, the miR-130b inhibitor decreased mRNA levels of MTP and fatty acid synthase (FAS) in HepG2 cells. However, dual-luciferase reporter assays indicated that MTP is not a direct target of miR-130b-3p. miR-130b overexpression did not alter de novo synthesized TG or the stability and secretion of apolipoprotein B 100. Interestingly, knockdown of phosphatase and tensin homolog (PTEN) blocked the upregulation of MTP mRNA induced by miR-130b. Finally, miR-130b-induced stimulation of VLDL secretion was also observed in a second hepatocyte cell culture model, immortalized human hepatocytes, confirming the effects observed in HepG2 cells. Overall, these data suggest a potential role for miR-130b in promoting hepatic VLDL assembly and secretion mediated by marked stimulation of MTP expression and TG mobilization. Thus miR-130b overexpression corrects the defect in VLDL production in HepG2 cells.
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Affiliation(s)
- Jing Zhang
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Ferdous Rastgar Jazii
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Mahdi Montazer Haghighi
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Danielle Alvares
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Lipei Liu
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Negar Khosraviani
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Khosrow Adeli
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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Metformin strongly affects transcriptome of peripheral blood cells in healthy individuals. PLoS One 2019; 14:e0224835. [PMID: 31703101 PMCID: PMC6839856 DOI: 10.1371/journal.pone.0224835] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 10/22/2019] [Indexed: 01/22/2023] Open
Abstract
Metformin is a commonly used antihyperglycaemic agent for the treatment of type 2 diabetes mellitus. Nevertheless, the exact mechanisms of action, underlying the various therapeutic effects of metformin, remain elusive. The goal of this study was to evaluate the alterations in longitudinal whole-blood transcriptome profiles of healthy individuals after a one-week metformin intervention in order to identify the novel molecular targets and further prompt the discovery of predictive biomarkers of metformin response. Next generation sequencing-based transcriptome analysis revealed metformin-induced differential expression of genes involved in intestinal immune network for IgA production and cytokine-cytokine receptor interaction pathways. Significantly elevated faecal sIgA levels during administration of metformin, and its correlation with the expression of genes associated with immune response (CXCR4, HLA-DQA1, MAP3K14, TNFRSF21, CCL4, ACVR1B, PF4, EPOR, CXCL8) supports a novel hypothesis of strong association between metformin and intestinal immune system, and for the first time provide evidence for altered RNA expression as a contributing mechanism of metformin’s action. In addition to universal effects, 4 clusters of functionally related genes with a subject-specific differential expression were distinguished, including genes relevant to insulin production (HNF1B, HNF1A, HNF4A, GCK, INS, NEUROD1, PAX4, PDX1, ABCC8, KCNJ11) and cholesterol homeostasis (APOB, LDLR, PCSK9). This inter-individual variation of the metformin effect on the transcriptional regulation goes in line with well-known variability of the therapeutic response to the drug.
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Traber MG, Leonard SW, Ebenuwa I, Violet PC, Wang Y, Niyyati M, Padayatty S, Tu H, Courville A, Bernstein S, Choi J, Shamburek R, Smith S, Head B, Bobe G, Ramakrishnan R, Levine M. Vitamin E absorption and kinetics in healthy women, as modulated by food and by fat, studied using 2 deuterium-labeled α-tocopherols in a 3-phase crossover design. Am J Clin Nutr 2019; 110:1148-1167. [PMID: 31495886 PMCID: PMC6821549 DOI: 10.1093/ajcn/nqz172] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 07/05/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Determining the human vitamin E [α-tocopherol (α-T)] requirement is difficult, and novel approaches to assess α-T absorption and trafficking are needed. OBJECTIVE We hypothesized that the dual-isotope technique, using 2 deuterium-labeled [intravenous (IV) d6- and oral d3-] α-T, would be effective in determining α-T fractional absorption. Further, defined liquid meal (DLM) fat or fasting would modulate α-T fractional absorption and lipoprotein transport. METHODS A 3-phase cr ossover design was used. At 0 h, participants received IV d6-α-T and consumed d3-α-T with a 600-kcal DLM (40% or 0% fat) followed by controlled meals or by the 0% fat DLM, a 12-h fast, and then controlled meals. Blood samples and fecal samples were collected at intervals and analyzed by LC-MS. Pharmacokinetic parameters were calculated from plasma tracer concentrations and enrichments. Fractional absorption was calculated from d3- to d6-α-T areas under the curve, from a novel mathematical model, and from the balance method (oral d3-α-T minus fecal d3-α-T excreted). RESULTS Estimated α-T fractional absorption during the 40% fat intervention was 55% ± 3% (mean ± SEM; n = 10), which was 9% less than during the 0% fat intervention (64% ± 3%, n = 10; P < 0.02). Fasting had no apparent effect (56% ± 3%, n = 7), except it slowed plasma oral d3-α-T appearance. Both balance data and model outcomes confirmed that the DLM fat did not potentiate d3-α-T absorption. During the IV emulsion clearance, HDL rapidly acquired d6-α-T (21 ± 2 nmol/L plasma per minute). During the first 8 h postdosing, triglyceride-rich lipoproteins (TRLs) were preferentially d3-α-T enriched relative to LDL or HDL, showing the TRL precursor role. CONCLUSIONS Quantitatively, α-T absorption is not limited by fat absence or by fasting. However, α-T leaves the intestine by a process that is prolonged during fasting and potentiated by eating, suggesting that α-T absorption is highly dependent on chylomicron assembly processes. This trial was registered at clinicaltrials.gov as NCT00862433.
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Affiliation(s)
- Maret G Traber
- Linus Pauling Institute, Oregon State University, Corvallis, OR, USA,School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA,Address correspondence to MGT (e-mail: )
| | - Scott W Leonard
- Linus Pauling Institute, Oregon State University, Corvallis, OR, USA
| | - Ifechukwude Ebenuwa
- Molecular and Clinical Nutrition Section, Intramural Research Program, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Pierre-Christian Violet
- Molecular and Clinical Nutrition Section, Intramural Research Program, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Yu Wang
- Molecular and Clinical Nutrition Section, Intramural Research Program, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Mahtab Niyyati
- Molecular and Clinical Nutrition Section, Intramural Research Program, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Sebastian Padayatty
- Molecular and Clinical Nutrition Section, Intramural Research Program, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Hongbin Tu
- Molecular and Clinical Nutrition Section, Intramural Research Program, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Amber Courville
- Clinical Center Nutrition Department, Oregon State University, Corvallis, OR, USA
| | - Shanna Bernstein
- Clinical Center Nutrition Department, Oregon State University, Corvallis, OR, USA
| | - Jaewoo Choi
- Linus Pauling Institute, Oregon State University, Corvallis, OR, USA
| | - Robert Shamburek
- Cardiovascular Branch, Intramural Research Program, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Sheila Smith
- Molecular and Clinical Nutrition Section, Intramural Research Program, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Brian Head
- Linus Pauling Institute, Oregon State University, Corvallis, OR, USA
| | - Gerd Bobe
- Linus Pauling Institute, Oregon State University, Corvallis, OR, USA
| | - Rajasekhar Ramakrishnan
- Department of Pediatrics, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Mark Levine
- Molecular and Clinical Nutrition Section, Intramural Research Program, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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Feng J, Yang J, Chang Y, Qiao L, Dang H, Luo K, Guo H, An Y, Ma C, Shao H, Tian J, Yuan Y, Xie L, Xing W, Cheng J. Caffeine-free hawk tea lowers cholesterol by reducing free cholesterol uptake and the production of very-low-density lipoprotein. Commun Biol 2019; 2:173. [PMID: 31098406 PMCID: PMC6506518 DOI: 10.1038/s42003-019-0396-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 03/21/2019] [Indexed: 02/08/2023] Open
Abstract
Medicinal plants show important therapeutic value in chronic disease treatment. However, due to their diverse ingredients and complex biological effects, the molecular mechanisms of medicinal plants are yet to be explored. By means of several high-throughput platforms, here we show hawk tea extract (HTE) inhibits Niemann-Pick C1-like 1 (NPC1L1)-mediated free cholesterol uptake, thereby inducing the transcription of low-density lipoprotein receptor (LDLR) downstream of the sterol response element binding protein 2 (SREBP2) pathway. Meanwhile, HTE suppresses hepatocyte nuclear factor 4α (HNF4α)-mediated transcription of microsomal triglyceride transfer protein (MTP) and apolipoprotein B (APOB), thereby decreasing the production of very-low-density lipoprotein. The catechin EGCG ((-)-epigallocatechin gallate) and the flavonoids kaempferol and quercetin are identified as the bioactive components responsible for the effects on the NPC1L1-SREBP2-LDLR axis and HNF4α-MTP/APOB axis, respectively. Overall, hawk tea works as a previously unrecognized cholesterol-lowering agent in a multi-target and multi-component manner.
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Affiliation(s)
- Juan Feng
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Jian Yang
- State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, 100700 Beijing, China
| | - Yujun Chang
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Liansheng Qiao
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Honglei Dang
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Kun Luo
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Hongyan Guo
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Yannan An
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Chengmei Ma
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Hong Shao
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Jie Tian
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Yuan Yuan
- State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, 100700 Beijing, China
| | - Lan Xie
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Wanli Xing
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Jing Cheng
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
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Song Y, Zhu J, Wang T, Zhang C, Yang F, Guo X, Liu P, Cao H, Hu G. Effect of Ultra-fine Traditional Chinese Medicine Compounds on Regulation of Lipid Metabolism and Reduction in Egg Cholesterol of Laying Hens. BRAZILIAN JOURNAL OF POULTRY SCIENCE 2018. [DOI: 10.1590/1806-9061-2017-0466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Y Song
- Jiangxi Agricultural University, P. R. China
| | - J Zhu
- Jiangxi Agricultural University, P. R. China
| | - T Wang
- Jiangxi Agricultural University, P. R. China
| | - C Zhang
- Jiangxi Agricultural University, P. R. China
| | - F Yang
- Jiangxi Agricultural University, P. R. China
| | - X Guo
- Jiangxi Agricultural University, P. R. China
| | - P Liu
- Jiangxi Agricultural University, P. R. China
| | - H Cao
- Jiangxi Agricultural University, P. R. China
| | - G Hu
- Jiangxi Agricultural University, P. R. China
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11
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Tetrahydrobenzothiophene carboxamides: Beyond the kinase domain and into the fatty acid realm. Bioorg Med Chem Lett 2017; 27:4462-4466. [DOI: 10.1016/j.bmcl.2017.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 08/01/2017] [Accepted: 08/03/2017] [Indexed: 11/21/2022]
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Manchekar M, Kapil R, Sun Z, Segrest JP, Dashti N. Relationship between Amphipathic β Structures in the β 1 Domain of Apolipoprotein B and the Properties of the Secreted Lipoprotein Particles in McA-RH7777 Cells. Biochemistry 2017; 56:4084-4094. [PMID: 28702990 DOI: 10.1021/acs.biochem.6b01174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Our previous studies demonstrated that the first 1000 amino acid residues (the βα1 domain) of human apolipoprotein (apo) B-100, termed apoB:1000, are required for the initiation of lipoprotein assembly and the formation of a monodisperse stable phospholipid (PL)-rich particle. The objectives of this study were (a) to assess the effects on the properties of apoB truncates undergoing sequential inclusion of the amphipathic β strands in the 700 N-terminal residues of the β1 domain of apoB-100 and (b) to identify the subdomain in the β1 domain that is required for the formation of a microsomal triglyceride transfer protein (MTP)-dependent triacylglycerol (TAG)-rich apoB-containing particle. Characterization of particles secreted by stable transformants of McA-RH7777 cells demonstrated the following. (1) The presence of amphipathic β strands in the 200 N-terminal residues of the β1 domain resulted in the secretion of apoB truncates (apoB:1050 to apoB:1200) as both lipidated and lipid-poor particles. (2) Inclusion of residues 300-700 of the β1 domain led to the secretion of apoB:1300, apoB:1400, apoB:1500, and apoB:1700 predominantly as lipidated particles. (3) Particles containing residues 1050-1500 were all rich in PL. (4) There was a marked increase in the lipid loading capacity and TAG content of apoB:1700-containing particles. (5) Only the level of secretion of apoB:1700 was markedly diminished by MTP inhibitor BMS-197636. These results suggest that apoB:1700 marks the threshold for the formation of a TAG-rich particle and support the concept that MTP participates in apoB assembly and secretion at the stage where particles undergo a transition from PL-rich to TAG-rich.
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Affiliation(s)
| | | | | | - Jere P Segrest
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
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Djafarzadeh S, Vuda M, Jeger V, Takala J, Jakob SM. The Effects of Fentanyl on Hepatic Mitochondrial Function. Anesth Analg 2017; 123:311-25. [PMID: 27089001 DOI: 10.1213/ane.0000000000001280] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Remifentanil interferes with hepatic mitochondrial function. The aim of the present study was to evaluate whether hepatic mitochondrial function is affected by fentanyl, a more widely used opioid than remifentanil. METHODS Human hepatoma HepG2 cells were exposed to fentanyl or pretreated with naloxone (an opioid receptor antagonist) or 5-hydroxydecanoate (5-HD, an inhibitor of mitochondrial adenosine triphosphate (ATP)-sensitive potassium [mitoKATP] channels), followed by incubation with fentanyl. Mitochondrial function and metabolism were then analyzed. RESULTS Fentanyl marginally reduced maximal mitochondrial complex-specific respiration rates using exogenous substrates (decrease in medians: 11%-18%; P = 0.003-0.001) but did not affect basal cellular respiration rates (P = 0.834). The effect on stimulated respiration was prevented by preincubation with naloxone or 5-HD. Fentanyl reduced cellular ATP content in a dose-dependent manner (P < 0.001), an effect that was not significantly prevented by 5-HD and not explained by increased total ATPase concentration. However, in vitro ATPase activity of recombinant human permeability glycoprotein (an ATP-dependent drug efflux transporter) was significantly stimulated by fentanyl (P = 0.004). CONCLUSIONS Our data suggest that fentanyl reduces stimulated mitochondrial respiration of cultured human hepatocytes by a mechanism that is blocked by a mitoKATP channel antagonist. Increased energy requirements for fentanyl efflux transport may offer an explanation for the substantial decrease in cellular ATP concentration.
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Affiliation(s)
- Siamak Djafarzadeh
- From the *Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Switzerland; and †Department of Clinical Research, Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
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14
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Reyes-Soffer G, Moon B, Hernandez-Ono A, Dionizovik-Dimanovski M, Dionizovick-Dimanovski M, Jimenez J, Obunike J, Thomas T, Ngai C, Fontanez N, Donovan DS, Karmally W, Holleran S, Ramakrishnan R, Mittleman RS, Ginsberg HN. Complex effects of inhibiting hepatic apolipoprotein B100 synthesis in humans. Sci Transl Med 2016; 8:323ra12. [PMID: 26819195 DOI: 10.1126/scitranslmed.aad2195] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mipomersen is a 20mer antisense oligonucleotide (ASO) that inhibits apolipoprotein B (apoB) synthesis; its low-density lipoprotein (LDL)-lowering effects should therefore result from reduced secretion of very-low-density lipoprotein (VLDL). We enrolled 17 healthy volunteers who received placebo injections weekly for 3 weeks followed by mipomersen weekly for 7 to 9 weeks. Stable isotopes were used after each treatment to determine fractional catabolic rates and production rates of apoB in VLDL, IDL (intermediate-density lipoprotein), and LDL, and of triglycerides in VLDL. Mipomersen significantly reduced apoB in VLDL, IDL, and LDL, which was associated with increases in fractional catabolic rates of VLDL and LDL apoB and reductions in production rates of IDL and LDL apoB. Unexpectedly, the production rates of VLDL apoB and VLDL triglycerides were unaffected. Small interfering RNA-mediated knockdown of apoB expression in human liver cells demonstrated preservation of apoB secretion across a range of apoB synthesis. Titrated ASO knockdown of apoB mRNA in chow-fed mice preserved both apoB and triglyceride secretion. In contrast, titrated ASO knockdown of apoB mRNA in high-fat-fed mice resulted in stepwise reductions in both apoB and triglyceride secretion. Mipomersen lowered all apoB lipoproteins without reducing the production rate of either VLDL apoB or triglyceride. Our human data are consistent with long-standing models of posttranscriptional and posttranslational regulation of apoB secretion and are supported by in vitro and in vivo experiments. Targeting apoB synthesis may lower levels of apoB lipoproteins without necessarily reducing VLDL secretion, thereby lowering the risk of steatosis associated with this therapeutic strategy.
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Affiliation(s)
- Gissette Reyes-Soffer
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA.
| | - Byoung Moon
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | - Antonio Hernandez-Ono
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | | | | | - Jhonsua Jimenez
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | - Joseph Obunike
- Biological Sciences Department, New York City College of Technology, 300 Jay Street, Brooklyn, NY 11201, USA
| | - Tiffany Thomas
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | - Colleen Ngai
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | - Nelson Fontanez
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | - Daniel S Donovan
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | - Wahida Karmally
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | - Stephen Holleran
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | - Rajasekhar Ramakrishnan
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
| | | | - Henry N Ginsberg
- Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA.
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15
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All-In-One: Advanced preparation of Human Parenchymal and Non-Parenchymal Liver Cells. PLoS One 2015; 10:e0138655. [PMID: 26407160 PMCID: PMC4583235 DOI: 10.1371/journal.pone.0138655] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 09/02/2015] [Indexed: 02/06/2023] Open
Abstract
Background & Aims Liver cells are key players in innate immunity. Thus, studying primary isolated liver cells is necessary for determining their role in liver physiology and pathophysiology. In particular, the quantity and quality of isolated cells are crucial to their function. Our aim was to isolate a large quantity of high-quality human parenchymal and non-parenchymal cells from a single liver specimen. Methods Hepatocytes, Kupffer cells, liver sinusoidal endothelial cells, and stellate cells were isolated from liver tissues by collagenase perfusion in combination with low-speed centrifugation, density gradient centrifugation, and magnetic-activated cell sorting. The purity and functionality of cultured cell populations were controlled by determining their morphology, discriminative cell marker expression, and functional activity. Results Cell preparation yielded the following cell counts per gram of liver tissue: 2.0±0.4×107 hepatocytes, 1.8±0.5×106 Kupffer cells, 4.3±1.9×105 liver sinusoidal endothelial cells, and 3.2±0.5×105 stellate cells. Hepatocytes were identified by albumin (95.5±1.7%) and exhibited time-dependent activity of cytochrome P450 enzymes. Kupffer cells expressed CD68 (94.5±1.2%) and exhibited phagocytic activity, as determined with 1μm latex beads. Endothelial cells were CD146+ (97.8±1.1%) and exhibited efficient uptake of acetylated low-density lipoprotein. Hepatic stellate cells were identified by the expression of α-smooth muscle actin (97.1±1.5%). These cells further exhibited retinol (vitamin A)-mediated autofluorescence. Conclusions Our isolation procedure for primary parenchymal and non-parenchymal liver cells resulted in cell populations of high purity and quality, with retained physiological functionality in vitro. Thus, this system may provide a valuable tool for determining liver function and disease.
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16
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Green CJ, Johnson D, Amin HD, Sivathondan P, Silva MA, Wang LM, Stevanato L, McNeil CA, Miljan EA, Sinden JD, Morten KJ, Hodson L. Characterization of lipid metabolism in a novel immortalized human hepatocyte cell line. Am J Physiol Endocrinol Metab 2015; 309:E511-22. [PMID: 26126685 PMCID: PMC4572456 DOI: 10.1152/ajpendo.00594.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 06/15/2015] [Indexed: 02/06/2023]
Abstract
The development of hepatocyte cell models that represent fatty acid partitioning within the human liver would be beneficial for the study of the development and progression of nonalcoholic fatty liver disease (NAFLD). We sought to develop and characterize a novel human liver cell line (LIV0APOLY) to establish a model of lipid accumulation using a physiological mixture of fatty acids under low- and high-glucose conditions. LIV0APOLY cells were compared with a well-established cell line (HepG2) and, where possible, primary human hepatocytes. LIV0APOLY cells were found to proliferate and express some mature liver markers and were wild type for the PNPLA3 (rs738409) gene, whereas HepG2 cells carried the Ile(148)Met variant that is positively associated with liver fat content. Intracellular triglyceride content was higher in HepG2 than in LIV0APOLY cells; exposure to high glucose and/or exogenous fatty acids increased intracellular triglyceride in both cell lines. Triglyceride concentrations in media were higher from LIV0APOLY compared with HepG2 cells. Culturing LIV0APOLY cells in high glucose increased a marker of endoplasmic reticulum stress and attenuated insulin-stimulated Akt phosphorylation whereas low glucose and exogenous fatty acids increased AMPK phosphorylation. Although LIV0APOLY cells and primary hepatocytes stored similar amounts of exogenous fatty acids as triglyceride, more exogenous fatty acids were partitioned toward oxidation in the LIV0APOLY cells than in primary hepatocytes. LIV0APOLY cells offer the potential to be a renewable cellular model for studying the effects of exogenous metabolic substrates on fatty acid partitioning; however, their usefulness as a model of lipoprotein metabolism needs to be further explored.
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Affiliation(s)
- Charlotte J Green
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | | | - Harsh D Amin
- ReNeuron Group, Guildford, Surrey, United Kingdom
| | - Pamela Sivathondan
- Nuffield Department of Obstetrics and Gynaecology, The Women's Centre, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Michael A Silva
- Department of Hepatobiliary and Pancreatic Surgery, Oxford University Hospital NHS Trust, Churchill Hospital, Oxford, United Kingdom; and
| | - Lai Mun Wang
- Department of Cellular Pathology, Oxford University Hospitals, Oxford, United Kingdom
| | | | - Catriona A McNeil
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | | | | | - Karl J Morten
- Nuffield Department of Obstetrics and Gynaecology, The Women's Centre, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Leanne Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom;
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17
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Fabbrini E, Magkos F. Hepatic Steatosis as a Marker of Metabolic Dysfunction. Nutrients 2015; 7:4995-5019. [PMID: 26102213 PMCID: PMC4488828 DOI: 10.3390/nu7064995] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 06/05/2015] [Accepted: 06/15/2015] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the liver manifestation of the complex metabolic derangements associated with obesity. NAFLD is characterized by excessive deposition of fat in the liver (steatosis) and develops when hepatic fatty acid availability from plasma and de novo synthesis exceeds hepatic fatty acid disposal by oxidation and triglyceride export. Hepatic steatosis is therefore the biochemical result of an imbalance between complex pathways of lipid metabolism, and is associated with an array of adverse changes in glucose, fatty acid, and lipoprotein metabolism across all tissues of the body. Intrahepatic triglyceride (IHTG) content is therefore a very good marker (and in some cases may be the cause) of the presence and the degree of multiple-organ metabolic dysfunction. These metabolic abnormalities are likely responsible for many cardiometabolic risk factors associated with NAFLD, such as insulin resistance, type 2 diabetes mellitus, and dyslipidemia. Understanding the factors involved in the pathogenesis and pathophysiology of NAFLD will lead to a better understanding of the mechanisms responsible for the metabolic complications of obesity, and hopefully to the discovery of novel effective treatments for their reversal.
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Affiliation(s)
- Elisa Fabbrini
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Faidon Magkos
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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18
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Macri EV, Lifshitz F, Alsina E, Juiz N, Zago V, Lezón C, Rodriguez PN, Schreier L, Boyer PM, Friedman SM. Monounsaturated fatty acids-rich diets in hypercholesterolemic-growing rats. Int J Food Sci Nutr 2015; 66:400-8. [PMID: 25830945 DOI: 10.3109/09637486.2015.1025719] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The effects of replacing dietary saturated fat by different monounsaturated fatty acid (ω-9MUFA) sources on serum lipids, body fat and bone in growing hypercholesterolemic rats were studied. Rats received one of the six different diets: AIN-93G (control, C); extra virgin olive oil (OO) + C; high-oleic sunflower oil (HOSO) + C or atherogenic diet (AT) for 8 weeks; the remaining two groups received AT for 3 weeks and then, the saturated fat was replaced by an oil mixture of soybean oil added with OO or HOSO for 5 weeks. Rats consuming MUFA-rich diets showed the highest body fat, hepatic index and epididymal, intestinal and perirenal fat, and triglycerides. T-chol and non-HDL-chol were increased in HOSO rats but decreased in OO rats. Bone mineral content and density were higher in both OO and HOSO groups than in AT rats. This study casts caution to the generalization of the benefits of MUFA for the treatment of hypercholesterolemia.
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Affiliation(s)
- Elisa V Macri
- Department of Biochemistry, School of Dentistry, University of Buenos Aires , Buenos Aires , Argentina
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19
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Dose response of endotoxin on hepatocyte and muscle mitochondrial respiration in vitro. BIOMED RESEARCH INTERNATIONAL 2015; 2015:353074. [PMID: 25649304 PMCID: PMC4306363 DOI: 10.1155/2015/353074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 08/22/2014] [Accepted: 09/08/2014] [Indexed: 01/02/2023]
Abstract
Introduction. Results on mitochondrial dysfunction in sepsis are controversial. We aimed to assess effects of LPS at wide dose and time ranges on hepatocytes and isolated skeletal muscle mitochondria. Methods. Human hepatocellular carcinoma cells (HepG2) were exposed to placebo or LPS (0.1, 1, and 10 μg/mL) for 4, 8, 16, and 24 hours and primary human hepatocytes to 1 μg/mL LPS or placebo (4, 8, and 16 hours). Mitochondria from porcine skeletal muscle samples were exposed to increasing doses of LPS (0.1–100 μg/mg) for 2 and 4 hours. Respiration rates of intact and permeabilized cells and isolated mitochondria were measured by high-resolution respirometry. Results. In HepG2 cells, LPS reduced mitochondrial membrane potential and cellular ATP content but did not modify basal respiration. Stimulated complex II respiration was reduced time-dependently using 1 μg/mL LPS. In primary human hepatocytes, stimulated mitochondrial complex II respiration was reduced time-dependently using 1 μg/mL LPS. In isolated porcine skeletal muscle mitochondria, stimulated respiration decreased at high doses (50 and 100 μg/mL LPS). Conclusion. LPS reduced cellular ATP content of HepG2 cells, most likely as a result of the induced decrease in membrane potential. LPS decreased cellular and isolated mitochondrial respiration in a time-dependent, dose-dependent and complex-dependent manner.
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20
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Green CJ, Pramfalk C, Morten KJ, Hodson L. From whole body to cellular models of hepatic triglyceride metabolism: man has got to know his limitations. Am J Physiol Endocrinol Metab 2015; 308:E1-20. [PMID: 25352434 PMCID: PMC4281685 DOI: 10.1152/ajpendo.00192.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The liver is a main metabolic organ in the human body and carries out a vital role in lipid metabolism. Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases, encompassing a spectrum of conditions from simple fatty liver (hepatic steatosis) through to cirrhosis. Although obesity is a known risk factor for hepatic steatosis, it remains unclear what factor(s) is/are responsible for the primary event leading to retention of intrahepatocellular fat. Studying hepatic processes and the etiology and progression of disease in vivo in humans is challenging, not least as NAFLD may take years to develop. We present here a review of experimental models and approaches that have been used to assess liver triglyceride metabolism and discuss their usefulness in helping to understand the aetiology and development of NAFLD.
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Affiliation(s)
- Charlotte J Green
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford United Kingdom; and
| | - Camilla Pramfalk
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford United Kingdom; and
| | - Karl J Morten
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Leanne Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford United Kingdom; and
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21
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Salter AM, White DA. Effects of Dietary Fat on Cholesterol Metabolism: Regulation of Plasma LDL Concentrations. Nutr Res Rev 2013; 9:241-57. [PMID: 19094272 DOI: 10.1079/nrr19960013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- A M Salter
- Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington Campus, Loughborough, Leics LE12 5RD
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22
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He P, Geng L, Mao D, Wang Z, Xu C. Production, preliminary characterization, and bioactivities of exopolysaccharides from Pleurotus geesteranus 5(#). Prep Biochem Biotechnol 2013; 43:108-22. [PMID: 23215658 DOI: 10.1080/10826068.2012.712078] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The optimal culture conditions of exopolysaccharides (EPS) production in submerged culture medium by Pleurotus geesteranus 5(#) were determined using an orthogonal matrix method. The optimal defined medium (per liter) was 60.0 g maltose, 5.0 g tryptone, 1 mM NaCl, 5 mM KH(2)PO(4), and initial pH 6.0 at 28 °C. In the optimal culture medium, the maximum EPS production was 16.97 g/L in a shake flask. Two groups of EPSs (designated as Fr-I and Fr-II) were obtained from the culture filtrates by size exclusion chromatography (SEC), and their molecular characteristics were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The approximate weight-average molar masses of the Fr-I and Fr-II of EPS were determined to be 3.263 × 10(4) and 5.738 × 10(3) g/mol, respectively. The low values of polydispersity ratio (1.176 and 1.124 for Fr-I and Fr-II, respectively) of EPSs mean that these EPS molecules exist much less dispersed in aqueous solution without forming large aggregates. Furthermore, the experiments in vitro indicated that P. geesteranus 5(#) EPS exhibit high antitumor and antioxidative effects.
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Affiliation(s)
- Peixin He
- College of Food and Biological Engineering, Zhengzhou University of Light Industry, Zhengzhou, Henan, PR China
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23
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Very-low-density lipoprotein (VLDL)-producing and hepatitis C virus-replicating HepG2 cells secrete no more lipoviroparticles than VLDL-deficient Huh7.5 cells. J Virol 2013; 87:5065-80. [PMID: 23427158 DOI: 10.1128/jvi.01405-12] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In the plasma samples of hepatitis C virus (HCV)-infected patients, lipoviroparticles (LVPs), defined as (very-) low-density viral particles immunoprecipitated with anti-β-lipoproteins antibodies are observed. This HCV-lipoprotein association has major implications with respect to our understanding of HCV assembly, secretion, and entry. However, cell culture-grown HCV (HCVcc) virions produced in Huh7 cells, which are deficient for very-low-density lipoprotein (VLDL) secretion, are only associated with and dependent on apolipoprotein E (apoE), not apolipoprotein B (apoB), for assembly and infectivity. In contrast to Huh7, HepG2 cells can be stimulated to produce VLDL by both oleic acid treatment and inhibition of the MEK/extracellular signal-regulated kinase (ERK) pathway but are not permissive for persistent HCV replication. Here, we developed a new HCV cell culture model to study the interaction between HCV and lipoproteins, based on engineered HepG2 cells stably replicating a blasticidin-tagged HCV JFH1 strain (JB). Control Huh7.5-JB as well as HepG2-JB cell lines persistently replicated viral RNA and expressed viral proteins with a subcellular colocalization of double-stranded RNA (dsRNA), core, gpE2, and NS5A compatible with virion assembly. The intracellular RNA replication level was increased in HepG2-JB cells upon dimethyl sulfoxide (DMSO) treatment, MEK/ERK inhibition, and NS5A overexpression to a level similar to that observed in Huh7.5-JB cells. Both cell culture systems produced infectious virions, which were surprisingly biophysically and biochemically similar. They floated at similar densities on gradients, contained mainly apoE but not apoB, and were not neutralized by anti-apoB antibodies. This suggests that there is no correlation between the ability of cells to simultaneously replicate HCV as well as secrete VLDL and their capacity to produce LVPs.
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Characterization of lipid and lipoprotein metabolism in primary human hepatocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:387-97. [PMID: 22951416 DOI: 10.1016/j.bbalip.2012.08.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Revised: 08/01/2012] [Accepted: 08/13/2012] [Indexed: 12/17/2022]
Abstract
Primary rodent hepatocytes and hepatoma cell lines are commonly used as model systems to elucidate and study potential drug targets for metabolic diseases such as obesity and atherosclerosis. However, if therapies are to be developed, it is essential that our knowledge gained from these systems is translatable to that of human. Here, we have characterized lipid and lipoprotein metabolism in primary human hepatocytes for comparison to rodent primary hepatocytes and human hepatoma cell lines. Primary human hepatocytes were maintained in collagen coated dishes in confluent monolayers for up to 3 days. We found primary human hepatocytes were viable, underwent lipid synthesis, and were able to secret lipoproteins up to 3 days in culture. Furthermore, the lipoprotein profile secreted by primary human hepatocytes was comparable to that found in human plasma; this contrasts with primary rodent hepatocytes and human hepatoma cells. We also investigated the pharmacological effects of nicotinic acid (niacin, NA), a potent dyslipidemic drug, on hepatic lipid synthesis and lipoprotein secretion. We found NA increased the expression of ATP-binding cassette transporter A1 in primary human hepatocytes, which may potentially explain how NA increases plasma high-density lipoproteins in humans. In conclusion, primary human hepatocytes are a more relevant model to study lipid synthesis and lipoprotein secretion than hepatoma cells or rodent primary hepatocyte models. Further research needs to be done to maintain liver specific functions of primary human hepatocytes in prolonged cultures for these cells to be a viable model.
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25
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SUZUKI Y, SONG SH, SATO K, SO KH, ARDIYANTI A, KITAYAMA S, HONG YH, LEE SD, CHOI KC, HAGINO A, KATOH K, ROH SG. Chemerin analog regulates energy metabolism in sheep. Anim Sci J 2012; 83:263-7. [DOI: 10.1111/j.1740-0929.2011.01002.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Moon BC, Hernandez-Ono A, Stiles B, Wu H, Ginsberg HN. Apolipoprotein B secretion is regulated by hepatic triglyceride, and not insulin, in a model of increased hepatic insulin signaling. Arterioscler Thromb Vasc Biol 2011; 32:236-46. [PMID: 22155452 DOI: 10.1161/atvbaha.111.241356] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVE States of insulin resistance, hyperinsulinemia, and hepatic steatosis are associated with increased secretion of triglycerides (TG) and apolipoprotein B (apoB), even though insulin targets apoB for degradation. We used hepatic-specific "phosphatase and tensin homologue deleted on chromosome 10" (Pten) knockout (hPten-ko) mice, with increased hepatic insulin signaling, to determine the relative roles of insulin signaling and hepatic TG in regulating apoB secretion. METHODS AND RESULTS TG and apoB secretion was elevated in hPten-ko mice. When hepatic TG was reduced by inhibition of diacylglycerol acyltransferase 1/diacylglycerol acyltransferase 2 or sterol regulatory element-binding protein-1c, both TG secretion and apoB secretion fell without changes in hepatic insulin signaling. Acute reconstitution of hPten reduced hepatic TG content, and both TG and apoB secretion fell within 4 days despite decreased hepatic insulin signaling. Acute depletion of hepatic Pten by adenoviral introduction of Cre into Pten floxed mice caused steatosis within 4 days, and secretion of both TG and apoB increased despite increased hepatic insulin signaling. Even when steatosis after acute Pten depletion was prevented by pretreatment with SREBP-1c antisense oligonucleotides, apoB secretion was not reduced after 4 days. Ex vivo results were in primary hepatocytes were similar. CONCLUSIONS Either hepatic TG is the dominant regulator of apoB secretion or any inhibitory effects of hepatic insulin signaling on apoB secretion is very short-lived.
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Affiliation(s)
- Byoung C Moon
- Irving Institute for Clinical and Translational Research, PH10-305, Columbia University, 630 West 168th Street, New York, NY 10032, USA
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27
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Caviglia JM, Gayet C, Ota T, Hernandez-Ono A, Conlon DM, Jiang H, Fisher EA, Ginsberg HN. Different fatty acids inhibit apoB100 secretion by different pathways: unique roles for ER stress, ceramide, and autophagy. J Lipid Res 2011; 52:1636-51. [PMID: 21719579 DOI: 10.1194/jlr.m016931] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Although short-term incubation of hepatocytes with oleic acid (OA) stimulates secretion of apolipoprotein B100 (apoB100), exposure to higher doses of OA for longer periods inhibits secretion in association with induction of endoplasmic reticulum (ER) stress. Palmitic acid (PA) induces ER stress, but its effects on apoB100 secretion are unclear. Docosahexaenoic acid (DHA) inhibits apoB100 secretion, but its effects on ER stress have not been studied. We compared the effects of each of these fatty acids on ER stress and apoB100 secretion in McArdle RH7777 (McA) cells: OA and PA induced ER stress and inhibited apoB100 secretion at higher doses; PA was more potent because it also increased the synthesis of ceramide. DHA did not induce ER stress but was the most potent inhibitor of apoB100 secretion, acting via stimulation of autophagy. These unique effects of each fatty acid were confirmed when they were infused into C57BL6J mice. Our results suggest that when both increased hepatic secretion of VLDL apoB100 and hepatic steatosis coexist, reducing ER stress might alleviate hepatic steatosis but at the expense of increased VLDL secretion. In contrast, increasing autophagy might reduce VLDL secretion without causing steatosis.
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Affiliation(s)
- Jorge Matias Caviglia
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA
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Inoue N, Nagao K, Sakata K, Yamano N, Gunawardena PER, Han SY, Matsui T, Nakamori T, Furuta H, Takamatsu K, Yanagita T. Screening of soy protein-derived hypotriglyceridemic di-peptides in vitro and in vivo. Lipids Health Dis 2011; 10:85. [PMID: 21600040 PMCID: PMC3116501 DOI: 10.1186/1476-511x-10-85] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 05/22/2011] [Indexed: 11/17/2022] Open
Abstract
Background Soy protein and soy peptides have attracted considerable attention because of their potentially beneficial biological properties, including antihypertensive, anticarcinogenic, and hypolipidemic effects. Although soy protein isolate contains several bioactive peptides that have distinct physiological activities in lipid metabolism, it is not clear which peptide sequences are responsible for the triglyceride (TG)-lowering effects. In the present study, we investigated the effects of soy protein-derived peptides on lipid metabolism, especially TG metabolism, in HepG2 cells and obese Otsuka Long-Evans Tokushima fatty (OLETF) rats. Results In the first experiment, we found that soy crude peptide (SCP)-LD3, which was prepared by hydrolyze of soy protein isolate with endo-type protease, showed hypolipidemic effects in HepG2 cells and OLETF rats. In the second experiment, we found that hydrophilic fraction, separated from SCP-LD3 with hydrophobic synthetic absorbent, revealed lipid-lowering effects in HepG2 cells and OLETF rats. In the third experiment, we found that Fraction-C (Frc-C) peptides, fractionated from hydrophilic peptides by gel permeation chromatography-high performance liquid chromatography, significantly reduced TG synthesis and apolipoprotein B (apoB) secretion in HepG2 cells. In the fourth experiment, we found that the fraction with 0.1% trifluoroacetic acid, isolated from Frc-C peptides by octadecylsilyl column chromatography, showed hypolipidemic effects in HepG2 cells. In the final experiment, we found that 3 di-peptides, Lys-Ala, Val-Lys, and Ser-Tyr, reduced TG synthesis, and Ser-Tyr additionally reduced apoB secretion in HepG2 cells. Conclusion Novel active peptides with TG-lowering effects from soy protein have been isolated.
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Affiliation(s)
- Nao Inoue
- Department of Applied Biochemistry and Food Science, Saga University, Saga 840-8502, Japan
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Lin Y, Vermeer MA, Bos W, van Buren L, Schuurbiers E, Miret-Catalan S, Trautwein EA. Molecular structures of citrus flavonoids determine their effects on lipid metabolism in HepG2 cells by primarily suppressing apoB secretion. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:4496-4503. [PMID: 21425871 DOI: 10.1021/jf1044475] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This study investigated the underlying mechanisms of action for blood lipid lowering effects of citrus flavonoids and their methoxylated analogues (n = 19; dose range: 0-100 μM) in HepG2 cells. Cholesterol (CH) and triglyceride (TG) syntheses were assessed by measuring the incorporation of (14)C-acetate and (14)C-glycerol, respectively, whereas apoB secretion was determined by ELISA. Results show that two polymethoxylated citrus flavonoids (PMFs), tangeretin and nobiletin, potently inhibited apoB secretion (IC(50) = 13 and 29 μM, respectively) and modestly inhibited CH synthesis (IC(50) = 49 and 68 μM) and TG synthesis (IC(50) = 14 and 73 μM), without effecting LDL-receptor activity. Other PMFs (e.g., sinensetin) and non-PMFs (e.g., hesperetin and naringenin) had only weak effects on CH and TG syntheses and apoB secretion (IC(50) > 100 μM). The structure-activity analysis indicated that a fully methoxylated A-ring of the flavonoid structure was associated with a potent inhibitory activity on hepatic apoB secretion. In conclusion, this study using HepG2 cells indicates that citrus flavonoids with a fully methoxylated A-ring may lower blood CH and TG concentrations primarily by suppressing hepatic apoB secretion as a main underlying mode of action.
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Affiliation(s)
- Yuguang Lin
- Unilever R&D Vlaardingen, Vlaardingen, The Netherlands.
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GREEN CURTISO, WHEATLEY ANDREWO, MCGROWDER DONOVANA, DILWORTH LOWELLL, ASEMOTA HELENN. HYPOLIPIDEMIC EFFECTS OF ORTANIQUE PEEL POLYMETHOXYLATED FLAVONES IN RATS WITH DIET-INDUCED HYPERCHOLESTEROLEMIA. J Food Biochem 2010. [DOI: 10.1111/j.1745-4514.2010.00479.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Norikura T, Mukai Y, Fujita S, Mikame K, Funaoka M, Sato S. Lignophenols Decrease Oleate-Induced Apolipoprotein-B Secretion in HepG2 Cells. Basic Clin Pharmacol Toxicol 2010; 107:813-7. [DOI: 10.1111/j.1742-7843.2010.00575.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Nagao K, Yamano N, Shirouchi B, Inoue N, Murakami S, Sasaki T, Yanagita T. Effects of citrus auraptene (7-geranyloxycoumarin) on hepatic lipid metabolism in vitro and in vivo. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:9028-9032. [PMID: 20681532 DOI: 10.1021/jf1020329] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Recent reports have shown that citrus auraptene (7-geranyloxycoumarin) possesses valuable pharmacological properties, including anticarcinogenic, anti-inflammatory, antihelicobacter, antigenotoxic, and neuroprotective effects. In the present study, we investigated the effect of dietary auraptene on hepatic lipid metabolism both in vitro and in vivo. Results suggested that auraptene has the ability to normalize lipid abnormalities in HepG2 hepatocytes. After 4 weeks of auraptene feeding, abdominal white adipose tissue weight and hepatic triglyceride (TG) levels were dose-dependently lowered in Otsuka Long-Evans Tokushima fatty (OLETF) rats. The activities of carnitine palmitoyltransferase, a key enzyme in mitochondrial fatty acid β-oxidation, and peroxisomal β-oxidation were markedly and dose-dependently enhanced in OLETF rat livers by auraptene feeding. Additionally, hepatic expression of acyl-CoA oxidase, the initial enzyme of the peroxisomal β-oxidation system, was significantly and dose-dependently enhanced by auraptene administration. These results suggest that auraptene administration alleviates obesity and hepatic TG accumulation in part through lipolysis enhancement in the livers of obese OLETF rats.
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Affiliation(s)
- Koji Nagao
- Laboratory of Nutrition Biochemistry, Department of Applied Biochemistry and Food Science, Saga University, Saga 840-8502, Japan
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Chen Z, Norris JY, Finck BN. Peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha) stimulates VLDL assembly through activation of cell death-inducing DFFA-like effector B (CideB). J Biol Chem 2010; 285:25996-6004. [PMID: 20551328 DOI: 10.1074/jbc.m110.141598] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Abnormalities in very low density lipoprotein (VLDL) assembly and secretion impact intrahepatic lipid homeostasis, plasma lipoprotein profile, and energy metabolism of distal peripheral tissues. We have evaluated the role of the transcriptional coactivator, the peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), in VLDL assembly and secretion. PGC-1alpha overexpression in HepG2 cells led to diminished rates of triglyceride (TG) synthesis but strongly stimulated VLDL-TG secretion, markedly increasing the efficiency of secretion of newly synthesized TG. PGC-1alpha overexpression increased the rate of secretion of apoB100 and promoted secretion of larger, less dense VLDL particles. PGC-1alpha overexpression in intact mouse liver also stimulated rates of VLDL TG secretion and attenuated hepatic TG accumulation resulting from high fat diet feeding. To determine the molecular mechanisms mediating the effect of PGC-1alpha on VLDL assembly, we evaluated the expression of several candidate mediators known to be involved in VLDL assembly or hepatic lipid homeostasis. Cell death-inducing DFFA-like effector B (CideB) expression was greatly induced by PGC-1alpha, and siRNA against CideB reversed the effects of PGC-1alpha on the secretion of TG and VLDL-sized particles by HepG2 cells, indicating that CideB is a critical mediator of stimulatory effects of PGC-1alpha on VLDL secretion. Collectively, these data suggest that PGC-1alpha plays an important role in partitioning cytoplasmic TG toward the VLDL secretory compartments and promoting VLDL secretion via transcriptional induction of CideB.
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Affiliation(s)
- Zhouji Chen
- Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA.
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Berthold HK, Mertens J, Birnbaum J, Brämswig S, Sudhop T, Barrett PHR, von Bergmann K, Gouni-Berthold I. Influence of simvastatin on apoB-100 secretion in non-obese subjects with mild hypercholesterolemia. Lipids 2010; 45:491-500. [PMID: 20461472 DOI: 10.1007/s11745-010-3420-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Accepted: 04/14/2010] [Indexed: 10/19/2022]
Abstract
Statins decrease apoB-100-containing lipoproteins by increasing their fractional catabolic rates through LDL receptor-mediated uptake. Their influence on hepatic secretion of these lipoproteins is controversial. The objective of the study was to examine the influence of simvastatin on the secretion of apoB-100-containing lipoproteins in fasting non-obese subjects. Turnover of apoB-100-containing lipoproteins was investigated using stable isotope-labeled tracers. Multicompartmental modeling was used to derive kinetic parameters. Eight male subjects (BMI 25 +/- 3 kg/m(2)) with mild hypercholesterolemia (LDL cholesterol 135 +/- 30 mg/dL) and normal triglycerides (111 +/- 44 mg/dL) were examined under no treatment (A), under chronic treatment with simvastatin 40 mg/day (B) and after an acute-on-chronic dosage of 80 mg simvastatin under chronic simvastatin treatment (C). Lipoprotein concentrations changed as expected under 40 mg/day simvastatin. Fractional catabolic rates increased in IDL and LDL but not in VLDL fractions versus control [VLDL +35% in B (n.s.) and +21% in C (n.s.); IDL +169% in B (P = 0.08) and +187% in C (P = 0.032); LDL +87% in B (P = 0.025) and +133% in C (P = 0.025)]. Chronic (B) and acute-on-chronic simvastatin treatment (C) did not affect lipoprotein production rates [VLDL -8 and -13%, IDL +47 and +38%, and LDL +19 and +30% in B and C, respectively (all comparisons n.s.)]. The data indicate that simvastatin does not influence the secretion of apoB-100-containing lipoproteins in non-obese subjects with near-normal LDL cholesterol concentrations.
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Affiliation(s)
- Heiner K Berthold
- Department of Clinical Pharmacology, University of Bonn, Bonn, Germany.
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Zhang L, Ramtohul Y, Gagné S, Styhler A, Wang H, Guay J, Huang Z. A multiplexed cell assay in HepG2 cells for the identification of delta-5, delta-6, and delta-9 desaturase and elongase inhibitors. ACTA ACUST UNITED AC 2010; 15:169-76. [PMID: 20086206 DOI: 10.1177/1087057109356208] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A multiplexed cell assay has been optimized to measure the activities of fatty acyl-CoA elongase, delta-5 desaturase (Delta5D), delta-6 desaturase (Delta6D), and delta-9 desaturase (Delta9D) together using (14)C-labeled tracers in HepG2 cells, which express the human stearoyl-CoA desaturase-1 isoform (SCD1) exclusively. The Delta5 and Delta9 desaturase activities are indexed by the efficient conversion of [1-(14)C]-eicosatrienoic acid (C20:3, cis-8,11,14) to (14)C-arachidonic acid (C20:4, cis-5,8,11,14) and the conversion of [1-(14)C]-stearic acid to (14)C-oleic acid (C18:1, cis-9), respectively. CP-74006 potently blocks the Delta5D activity with an IC(50) value of 20 nM and simplifies the metabolism of [1-(14)C]-alpha-linolenate (C18:3, cis-9,12,15) by accumulating (14)C-eicosatetraenoic acid (C20:4, cis-8,11,14,17) as the major (14)C-eicosatrienoic acid (C20:3, cis-11,14,17) and (14)C-docosatetraenoic acid (C22:4, cis-10,13,16,19) as the minor metabolites through Delta6 desaturation and elongation. This simplified metabolite spectrum enables the delineation of the Delta6D activity by comparing the combined Delta6D/elongase activity index of the (14)C-(C20:4/C18:3) ratio with the corresponding elongation index of the (14)C-(C20:3/C18:3) ratio following compound treatment. SC-26196 and sterculic acid specifically inhibit the Delta6D and Delta9D activities with an IC(50) value of 0.1 microM and 0.9 microM, respectively. This medium-throughput cell assay provides an efficient tool in the identification of specific desaturase and elongase inhibitors.
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Affiliation(s)
- Lei Zhang
- Merck Frosst Center for Therapeutic Research, Montreal, Canada
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Mulvihill EE, Allister EM, Sutherland BG, Telford DE, Sawyez CG, Edwards JY, Markle JM, Hegele RA, Huff MW. Naringenin prevents dyslipidemia, apolipoprotein B overproduction, and hyperinsulinemia in LDL receptor-null mice with diet-induced insulin resistance. Diabetes 2009; 58:2198-210. [PMID: 19592617 PMCID: PMC2750228 DOI: 10.2337/db09-0634] [Citation(s) in RCA: 217] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVE The global epidemic of metabolic syndrome and its complications demands rapid evaluation of new and accessible interventions. Insulin resistance is the central biochemical disturbance in the metabolic syndrome. The citrus-derived flavonoid, naringenin, has lipid-lowering properties and inhibits VLDL secretion from cultured hepatocytes in a manner resembling insulin. We evaluated whether naringenin regulates lipoprotein production and insulin sensitivity in the context of insulin resistance in vivo. RESEARCH DESIGN AND METHODS LDL receptor-null (Ldlr(-/-)) mice fed a high-fat (Western) diet (42% calories from fat and 0.05% cholesterol) become dyslipidemic, insulin and glucose intolerant, and obese. Four groups of mice (standard diet, Western, and Western plus 1% or 3% wt/wt naringenin) were fed ad libitum for 4 weeks. VLDL production and parameters of insulin and glucose tolerance were determined. RESULTS We report that naringenin treatment of Ldlr(-/-) mice fed a Western diet corrected VLDL overproduction, ameliorated hepatic steatosis, and attenuated dyslipidemia without affecting caloric intake or fat absorption. Naringenin 1) increased hepatic fatty acid oxidation through a peroxisome proliferator-activated receptor (PPAR) gamma coactivator 1alpha/PPARalpha-mediated transcription program; 2) prevented sterol regulatory element-binding protein 1c-mediated lipogenesis in both liver and muscle by reducing fasting hyperinsulinemia; 3) decreased hepatic cholesterol and cholesterol ester synthesis; 4) reduced both VLDL-derived and endogenously synthesized fatty acids, preventing muscle triglyceride accumulation; and 5) improved overall insulin sensitivity and glucose tolerance. CONCLUSIONS Thus, naringenin, through its correction of many of the metabolic disturbances linked to insulin resistance, represents a promising therapeutic approach for metabolic syndrome.
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Affiliation(s)
- Erin E. Mulvihill
- Department of Vascular Biology, Robarts Research Institute, London, Ontario, Canada
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
| | - Emma M. Allister
- Department of Vascular Biology, Robarts Research Institute, London, Ontario, Canada
| | - Brian G. Sutherland
- Department of Vascular Biology, Robarts Research Institute, London, Ontario, Canada
| | - Dawn E. Telford
- Department of Vascular Biology, Robarts Research Institute, London, Ontario, Canada
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Cynthia G. Sawyez
- Department of Vascular Biology, Robarts Research Institute, London, Ontario, Canada
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Jane Y. Edwards
- Department of Vascular Biology, Robarts Research Institute, London, Ontario, Canada
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Janet M. Markle
- Department of Vascular Biology, Robarts Research Institute, London, Ontario, Canada
| | - Robert A. Hegele
- Department of Vascular Biology, Robarts Research Institute, London, Ontario, Canada
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
- Blackburn Cardiovascular Genetics Laboratory, Robarts Research Institute, London, Ontario, Canada
| | - Murray W. Huff
- Department of Vascular Biology, Robarts Research Institute, London, Ontario, Canada
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
- Corresponding author: Murray W. Huff,
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Okamoto T, Kanemoto N, Ban T, Sudo T, Nagano K, Niki I. Establishment and characterization of a novel method for evaluating gluconeogenesis using hepatic cell lines, H4IIE and HepG2. Arch Biochem Biophys 2009; 491:46-52. [PMID: 19799852 DOI: 10.1016/j.abb.2009.09.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 09/24/2009] [Accepted: 09/24/2009] [Indexed: 02/03/2023]
Abstract
The liver gluconeogenic pathway is recognized as a target for treating diabetes mellitus. In this study, we attempted to establish a new method to evaluate gluconeogenesis using rat H4IIE hepatoma cells. High-density preculture and exposure to hypertonic solutions, which are known to upregulate the expression of gluconeogenic genes, enhanced glucose release (GR) promoted by gluconeogenic substrates (GS: 1mM pyruvate and 10mM lactate). Our method was also applicable to the human hepatoma HepG2 cells. Measurement of glycogen content in HepG2 cells revealed that GR was compensated by glycogenolysis in the basal state and was generated by gluconeogenesis in the presence of GS. The optimized conditions increased the expression of gluconeogenic genes in HepG2 cells. Insulin and metformin dose-dependently inhibited GR and 8-(4-chlorophenylthio)-cAMP (CPT-cAMP) increased it. These results suggest that the present method is useful to evaluate the effects of nutrients, hormones and hypoglycemic agents on hepatic gluconeogenesis.
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Affiliation(s)
- Takashi Okamoto
- First Institute of New Drug Discovery, Otsuka Pharmaceutical Co. Ltd., Kawauchi-cho, Tokushima, Japan
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Su Q, Tsai J, Xu E, Qiu W, Bereczki E, Santha M, Adeli K. Apolipoprotein B100 acts as a molecular link between lipid-induced endoplasmic reticulum stress and hepatic insulin resistance. Hepatology 2009; 50:77-84. [PMID: 19434737 DOI: 10.1002/hep.22960] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
UNLABELLED Accumulation of unfolded and misfolded proteins in the endoplasmic reticulum (ER) results in ER stress and lipid overload-induced ER stress has been implicated in the development of insulin resistance. Here, evidence is provided for a molecular link between hepatic apolipoprotein B100 (apoB100), induction of ER stress, and attenuated insulin signaling. First, in vivo upregulation of hepatic apoB100 by a lipogenic diet was found to be closely associated with ER stress and attenuated insulin signaling in the liver. Direct in vivo overexpression of human apoB100 in a mouse transgenic model further supported the link between excessive apoB100 expression and hepatic ER stress. Human apoB100 transgenic mice exhibited hypertriglyceridemia and hyperglycemia. In vitro, accumulation of cellular apoB100 by free fatty acid (oleate) stimulation or constant expression of wild-type or N-glycosylation mutant apoB50 in hepatic cells induced ER stress. This led to perturbed activation of glycogen synthase kinase 3 and glycogen synthase by way of the activation of c-Jun N-terminal kinase and suppression of insulin signaling cascade, suggesting that dysregulation of apoB was sufficient to disturb ER homeostasis and induce hepatic insulin resistance. Small interfering (si)RNA-mediated attenuation of elevated apoB level in the apoB50-expressing cells rescued cells from lipid-induced ER stress and reversed insulin insensitivity. CONCLUSION These findings implicate apoB100 as a molecular link between lipid-induced ER stress and hepatic insulin resistance.
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Affiliation(s)
- Qiaozhu Su
- Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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Levy E, Ménard D, Delvin E, Montoudis A, Beaulieu JF, Mailhot G, Dubé N, Sinnett D, Seidman E, Bendayan M. Localization, function and regulation of the two intestinal fatty acid-binding protein types. Histochem Cell Biol 2009; 132:351-67. [PMID: 19499240 DOI: 10.1007/s00418-009-0608-y] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2009] [Indexed: 01/20/2023]
Abstract
Although intestinal (I) and liver (L) fatty acid binding proteins (FABP) have been widely studied, the physiological significance of the presence of the two FABP forms (I- and L-FABP) in absorptive cells remains unknown as do the differences related to their distribution along the crypt-villus axis, regional expression, ontogeny and regulation in the human intestine. Our morphological experiments supported the expression of I- and L-FABP as early as 13 weeks of gestation. Whereas cytoplasmic immunofluorescence staining of L-FABP was barely detectable in the lower half of the villus and in the crypt epithelial cells, I-FABP was visualized in epithelial cells of the crypt-villus axis in all intestinal segments until the adult period in which the staining was maximized in the upper part of the villus. Immunoelectron microscopy revealed more intense labeling of L-FABP compared with I-FABP, accompanied with a heterogeneous distribution in the cytoplasm, microvilli and basolateral membranes. By western blot analysis, I- and L-FABP at 15 weeks of gestation appeared predominant in jejunum compared with duodenum, ileum, proximal and distal colon. Exploration of the maturation aspect documented a rise in L-FABP in adult tissues. Permanent transfections of Caco-2 cells with I-FABP cDNA resulted in decreased lipid export, apolipoprotein (apo) biogenesis and chylomicron secretion. Additionally, supplementation of Caco-2 with insulin, hydrocortisone and epidermal growth factor differentially modulated the expression of I- and L-FABP, apo B-48 and microsomal triglyceride transfer protein (MTP), emphasizing that these key proteins do not exhibit a parallel modulation. Overall, our findings indicate that the two FABPs display differences in localization, regulation and developmental pattern.
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Affiliation(s)
- Emile Levy
- Department of Nutrition, CHU-Sainte-Justine, University of Montreal, 3175 Côte Ste-Catherine Road, Montreal, QC, H3T 1C5, Canada.
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Ginsberg HN, Fisher EA. The ever-expanding role of degradation in the regulation of apolipoprotein B metabolism. J Lipid Res 2009; 50 Suppl:S162-S166. [PMID: 19050312 PMCID: PMC2674708 DOI: 10.1194/jlr.r800090-jlr200] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 12/02/2008] [Indexed: 11/17/2023] Open
Abstract
Apolipoprotein B (apoB) is the essential protein required for the assembly and secretion of chylomicrons from the small intestine and VLDLs from the liver. These lipoproteins, as well as their remnants and LDL, play key roles in the transport of dietary and endogenously synthesized lipids throughout the body. However, they can be involved in the initiation of atherosclerotic lesions in the vessel wall. Therefore, it is not surprising that the assembly of apoB-containing lipoproteins in the small intestine and liver is a highly regulated process. In particular, cotranslational and posttranslational targeting of apoB for degradation, regulated largely by the availability of the core lipids carried in the lipoprotein, by the types of dietary fatty acids consumed, and by the hormonal milieu, determines the number of chylomicrons or VLDL that are secreted. In this review, we summarize both older and more recent findings on the pathways of apoB degradation, focusing on events in the liver.
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Affiliation(s)
- Henry N Ginsberg
- Department of Medicine, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA.
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The sulfated polysaccharide porphyran reduces apolipoprotein B100 secretion and lipid synthesis in HepG2 cells. Biosci Biotechnol Biochem 2009; 73:447-9. [PMID: 19202270 DOI: 10.1271/bbb.80688] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The physiological effect of porphyran, a sulfated polysaccharides from an edible red alga, was studied in human hepatoma HepG2 cells. Porphyran supplementation significantly decreased apolipoprotein B100 secretion, and the reduction was partly associated with suppression of cellular lipid synthesis in HepG2 cells. This is the first study to elucidate the mechanism of the hypolipidemic effect of porphyran.
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Kang YJ, Jin UH, Chang HW, Son JK, Lee SH, Son KH, Chang YC, Lee YC, Kim CH. Inhibition of microsomal triglyceride transfer protein expression and atherogenic risk factor apolipoprotein B100 secretion by tanshinone IIA in HepG2 cells. Phytother Res 2008; 22:1640-5. [DOI: 10.1002/ptr.2542] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Jänis MT, Laaksonen R, Oresic M. Metabolomic strategies to identify tissue-specific effects of cardiovascular drugs. Expert Opin Drug Metab Toxicol 2008; 4:665-80. [PMID: 18611110 DOI: 10.1517/17425255.4.6.665] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND The number of patients eligible for cardiovascular therapies in general is forecast to increase substantially in the coming decades. However, the current list of potential future cardiovascular blockbuster drugs is alarmingly short. There is thus a clear need for innovative strategies to increase the efficiency of drug development pipelines by establishing new sensitive biomarkers to monitor drug efficacy and safety in the context of complexity of lipoprotein metabolism targeted by the cardiovascular drugs. METHODS Metabolomics is a discipline dedicated to the systematic study of small molecules in cells, tissues and biofluids. Since lipids (including cholesterol), as well as other metabolites, are key constituents of lipoprotein particles and are thus part of the complex lipoprotein metabolism that includes exchange of lipids and metabolites with peripheral tissues, cardiovascular drug safety and efficacy needs to be addressed in the context of systemic lipid metabolism. RESULTS/CONCLUSION Metabolomics, lipidomics in particular, is expected to make an important impact on the discovery and development of cardiovascular therapies.
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Affiliation(s)
- Minna T Jänis
- Zora Biosciences Oy, Biologinkuja 1, Espoo, FI-02150, Finland
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Manchekar M, Richardson PE, Sun Z, Liu Y, Segrest JP, Dashti N. Charged amino acid residues 997-1000 of human apolipoprotein B100 are critical for the initiation of lipoprotein assembly and the formation of a stable lipidated primordial particle in McA-RH7777 cells. J Biol Chem 2008; 283:29251-65. [PMID: 18725409 DOI: 10.1074/jbc.m804912200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
We previously demonstrated that a portion, or perhaps all, of the residues between 931 and 1000 of apolipoprotein (apo) B100 are required for the initiation of apoB-containing particle assembly. Based on our structural model of the first 1000 residues of apoB (designated as apoB:1000), we hypothesized that this domain folds into a three-sided lipovitellin-like "lipid pocket" via a hairpin-bridge mechanism. We proposed that salt bridges are formed between four tandem charged residues 717-720 in the turn of the hairpin bridge and four tandem complementary residues 997-1000 located at the C-terminal end of the model. To identify the specific motif within residues 931 and 1000 that is critical for apoB particle assembly, apoB:956 and apoB:986 were produced. To test the hairpin-bridge hypothesis, the following mutations were made: 1) residues 997-1000 deletion (apoB:996), 2) residues 717-720 deletion (apoB:1000Delta717-720), and 3) substitution of charged residues 997-1000 with alanines (apoB:996 + 4Ala). Characterization of particles secreted by stable transformants of McA-RH7777 cells demonstrated the following. 1) ApoB:956 did not form stable particles and was secreted as large lipid-rich aggregates. 2) ApoB:986 formed both a lipidated particle that was denser than HDL(3) and large lipid-rich aggregates. 3) Compared with wild-type apoB:1000, apoB:1000Delta717-720 displayed the following: (i) significantly diminished capacity to form intact lipidated particles and (ii) increased propensity to form large lipid-rich aggregates. 4) In striking contrast to wild-type apoB:1000, (i) apoB:996 and apoB:996 + 4Ala were highly susceptible to intracellular degradation, (ii) only a small proportion of the secreted proteins formed stable HDL(3)-like lipoproteins, and (iii) a majority of the secreted proteins formed large lipid-rich aggregates. We conclude that the first 1000 amino acid residues of human apoB100 are required for the initiation of nascent apoB-containing lipoprotein assembly, and residues 717-720 and 997-1000 play key roles in this process, perhaps via a hairpin-bridge mechanism.
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Affiliation(s)
- Medha Manchekar
- Department of Medicine, Basic Sciences Section, Atherosclerosis Research Unit, University of Alabama at Birmingham Medical Center, Birmingham, Alabama 35294, USA
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Nahmias Y, Goldwasser J, Casali M, van Poll D, Wakita T, Chung RT, Yarmush ML. Apolipoprotein B-dependent hepatitis C virus secretion is inhibited by the grapefruit flavonoid naringenin. Hepatology 2008; 47:1437-45. [PMID: 18393287 PMCID: PMC4500072 DOI: 10.1002/hep.22197] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
UNLABELLED Hepatitis C virus (HCV) infects over 3% of the world population and is the leading cause of chronic liver disease worldwide. HCV has long been known to associate with circulating lipoproteins, and its interactions with the cholesterol and lipid pathways have been recently described. In this work, we demonstrate that HCV is actively secreted by infected cells through a Golgi-dependent mechanism while bound to very low density lipoprotein (vLDL). Silencing apolipoprotein B (ApoB) messenger RNA in infected cells causes a 70% reduction in the secretion of both ApoB-100 and HCV. More importantly, we demonstrate that the grapefruit flavonoid naringenin, previously shown to inhibit vLDL secretion both in vivo and in vitro, inhibits the microsomal triglyceride transfer protein activity as well as the transcription of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase and acyl-coenzyme A:cholesterol acyltransferase 2 in infected cells. Stimulation with naringenin reduces HCV secretion in infected cells by 80%. Moreover, we find that naringenin is effective at concentrations that are an order of magnitude below the toxic threshold in primary human hepatocytes and in mice. CONCLUSION These results suggest a novel therapeutic approach for the treatment of HCV infection.
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Affiliation(s)
- Yaakov Nahmias
- Center for Engineering in Medicine, Shriners Burns Hospital, Boston, MA, USA.
| | - Jonathan Goldwasser
- Center for Engineering in Medicine, Shriners Burns Hospital, Boston, MA,Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA
| | - Monica Casali
- Center for Engineering in Medicine, Shriners Burns Hospital, Boston, MA,Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Daan van Poll
- Center for Engineering in Medicine, Shriners Burns Hospital, Boston, MA,Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Takaji Wakita
- National Institute of Infectious Diseases, Tokyo, Japan
| | - Raymond T. Chung
- Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Martin L. Yarmush
- Center for Engineering in Medicine, Shriners Burns Hospital, Boston, MA,Massachusetts General Hospital, Harvard Medical School, Boston, MA
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Liu Y, Wang Q, Pan YB, Gao ZJ, Liu YF, Chen SH. Effects of over-expressing resistin on glucose and lipid metabolism in mice. J Zhejiang Univ Sci B 2008; 9:44-50. [PMID: 18196612 PMCID: PMC2170468 DOI: 10.1631/jzus.b071479] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Accepted: 12/04/2007] [Indexed: 02/07/2023]
Abstract
Resistin, a newly discovered peptide hormone mainly secreted by adipose tissues, is present at high levels in serum of obese mice and may be a potential link between obesity and insulin resistance in rodents. However, some studies of rat and mouse models have associated insulin resistance and obesity with decreased resistin expression. In humans, no relationship between resistin level and insulin resistance or adiposity was observed. This suggests that additional studies are necessary to determine the specific role of resistin in the regulation of energy metabolism and adipogenesis. In the present study, we investigated the effect of resistin in vivo on glucose and lipid metabolism by over-expressing resistin in mice by intramuscular injection of a recombinant eukaryotic expression vector pcDNA3.1-Retn encoding porcine resistin gene. After injection, serum resistin and serum glucose (GLU) levels were significantly increased in the pcDNA3.1-Retn-treated mice; there was an obvious difference in total cholesterol (TC) level between the experiment and the control groups on Day 30. In pcDNA3.1-Retn-treated mice, both free fatty acid (FFA) and high density lipoprotein (HDL) cholesterol levels were markedly lower than those of control, whereas HDL cholesterol and triglyceride (TG) levels did not differ between the two groups. Furthermore, lipase activity was expressly lower on Day 20. Our data suggest that resistin over-expressed in mice might be responsible for insulin resistance and parameters related to glucose and lipid metabolism were changed accordingly.
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Affiliation(s)
- You Liu
- Biochemistry Center, Guangdong Ocean University, Zhanjiang 524088, China
| | - Qun Wang
- College of Agronomy, Guangdong Ocean University, Zhanjiang 524088, China
| | - Ying-bin Pan
- College of Agronomy, Guangdong Ocean University, Zhanjiang 524088, China
| | - Zhi-jie Gao
- College of Agronomy, Guangdong Ocean University, Zhanjiang 524088, China
| | - Yan-fen Liu
- Biochemistry Center, Guangdong Ocean University, Zhanjiang 524088, China
| | - Shao-hong Chen
- Biochemistry Center, Guangdong Ocean University, Zhanjiang 524088, China
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Jin UH, Kang YJ, Chang YC, Kim CH. Secretion of atherogenic risk factor apolipoprotein B-100 is increased by a potential mechanism of JNK/PKC-mediated insulin resistance in liver cells. J Cell Biochem 2008; 103:908-19. [PMID: 17647275 DOI: 10.1002/jcb.21462] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Apolipoprotein B-100 (ApoB) is the main protein of the atherogenic lipoproteins and plasma ApoB levels reflect the total numbers of atherogenic lipoproteins. Induction of insulin resistance was accompanied by a considerable rise in the production of hepatic very low density lipoprotein (VLDL) containing ApoB and triglyceride. Increased plasma levels of ApoB and triglyceride in VLDL are common characteristics of the dyslipidemia associated with insulin resistance and type 2 diabetes mellitus. Thus, we investigate whether phorbol 12-myristate-13-acetate (PMA)-induced insulin resistance affects the increase of ApoB secretion. PMA increased ApoB secretion and transcriptional level of microsomal triglyceride transfer protein (MTP). PMA treatment also resulted in increase of insulin receptor substrate 1 (IRS1) serine312 (Ser312) and serine1101 (Ser1101) phosphorylation and induction of IRS1 degradation. Additionally, PMA induced activation of c-jun N-terminal kinase (JNK) and protein kinase C (PKC) isoforms (alpha, betaI, delta, zeta, theta), and reduced AKT8 virus oncogene cellular homolog (AKT) activation in a time dependent manner. PMA-induced ApoB secretion, MTP promoter activities, and IRS1 degradation was significantly decreased by treatment of JNK and PKCs inhibitors. Orthovanadate, a potent tyrosine phosphatase inhibitor, increased tyrosine phosphorylation of IRS1 and decreased ApoB secretion of Chang liver cells although PMA was co-treated. From the results, it was concluded that PMA-induced insulin resistance, through induction of serine phosphorylation of IRS1 mediated by activated JNK and PKCs, increases ApoB secretion in Chang liver cells.
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Affiliation(s)
- Un-Ho Jin
- Molecular and Cellular Glycobiology Unit, Department of Biological Sciences, SungKyunKwan University, 300 Chunchun-Dong, Suwon, Kyunggi-Do 440-746, Korea
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Griffin BA, Zampelas A. Influence of Dietary Fatty Acids on the Atherogenic Lipoprotein Phenotype. Nutr Res Rev 2007; 8:1-26. [DOI: 10.1079/nrr19950004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Wei E, Alam M, Sun F, Agellon LB, Vance DE, Lehner R. Apolipoprotein B and triacylglycerol secretion in human triacylglycerol hydrolase transgenic mice. J Lipid Res 2007; 48:2597-606. [PMID: 17878493 DOI: 10.1194/jlr.m700320-jlr200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apolipoprotein B (apoB)-containing lipoproteins play a critical role in whole body lipid homeostasis and the pathogenesis of atherosclerosis. The assembly of hepatic apoB-containing lipoproteins, VLDL, is governed by the availability of lipids, including triacylglycerol (TG). The majority of TG associated with VLDL is derived from the hepatic cytoplasmic lipid stores by a process involving lipolysis followed by reesterification. Microsomal triacylglycerol hydrolase (TGH) has been demonstrated to play a role in the lipolysis/reesterification process. To evaluate the potential regulatory role of TGH in hepatic VLDL assembly, we developed inducible transgenic mice expressing a human TGH minigene under the control of the mouse metallothionein promoter. Induction of human TGH by zinc resulted in liver-specific expression of the enzyme associated with 3- to 4-fold increases in lipolytic activity that could be attenuated with a TGH-specific inhibitor. Augmented TGH activity led to increased secretion of newly synthesized apoB and plasma TG levels. These results suggest that increased hepatic expression of TGH leads to a more proatherogenic plasma lipid and apoB profile.
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Affiliation(s)
- Enhui Wei
- Department of Pediatrics, Canadian Institutes of Health Research Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
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Ruixing Y, Guangqin C, Yong W, Weixiong L, Dezhai Y, Shangling P. Effect of the 3'APOB-VNTR polymorphism on the lipid profiles in the Guangxi Hei Yi Zhuang and Han populations. BMC MEDICAL GENETICS 2007; 8:45. [PMID: 17640344 PMCID: PMC1939985 DOI: 10.1186/1471-2350-8-45] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2007] [Accepted: 07/17/2007] [Indexed: 11/10/2022]
Abstract
BACKGROUND Apolipoprotein (Apo) B is the major component of low-density lipoprotein (LDL), very low-density lipoprotein (VLDL) and chylomicrons. Many genetic polymorphisms of the Apo B have been described, associated with variation of lipid levels. However, very few studies have evaluated the effect of the variable number of tandem repeats region 3' of the Apo B gene (3'APOB-VNTR) polymorphism on the lipid profiles in the special minority subgroups in China. Thus, the present study was undertaken to study the effect of the 3'APOB-VNTR polymorphism on the serum lipid levels in the Guangxi Hei Yi Zhuang and Han populations. METHODS A total of 548 people of Hei Yi Zhuang were surveyed by a stratified randomized cluster sampling. The epidemiological survey was performed using internationally standardized methods. Serum lipid and apolipoprotein levels were measured. The 3'APOB-VNTR alleles were determined by polymerase chain reaction (PCR) followed by electrophoresis in polyacrylamide gels, and classified according to the number of repeats of a 15-bp hypervariable elements (HVE). The sequence of the most common allele was determined using the PCR and direct sequencing. The possible association between alleles of the 3'APOB-VNTR and lipid variables was examined. The results were compared with those in 496 people of Han who also live in that district. RESULTS Nineteen alleles ranging from 24 to 64 repeats were detected in both Hei Yi Zhuang and Han. HVE56 and HVE58 were not be detected in Hei Yi Zhuang whereas HVE48 and HVE62 were totally absent in Han. The frequencies of HVE26, HVE30, HVE46, heterozygote, and short alleles (< 38 repeats) were higher in Hei Yi Zhuang than in Han. But the frequencies of HVE34, HVE38, HVE40, homozygote, and long alleles (> or = 38 repeats) were lower in Hei Yi Zhuang than in Han (P < 0.05-0.01). The levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and Apo B in Hei Yi Zhuang but not in Han were higher in VNTR-LS (carrier of one long and one short alleles) than in VNTR-LL (the individual carrying two long alleles) genotypes. The levels of TC, triglycerides (TG), LDL cholesterol, and Apo B in Hei Yi Zhuang were higher in both HVE34 and HVE36 alleles than in HVE32 allele. The levels of TC, TG, HDL-C and Apo B in Hei Yi Zhuang were also higher in homozygotes than in heterozygotes. There were no significant differences in the detected lipid parameters between the VNTR-SS (carrier of two short alleles) and VNTR-LS or VNTR-LL genotypes in both ethnic groups. CONCLUSION There were significant differences of the 3'APOB-VNTR polymorphism between the Hei Yi Zhuang and Han populations. An association between the 3'APOB-VNTR polymorphism and serum lipid levels was observed in the Hei Yi Zhuang but not in the Han populations.
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Affiliation(s)
- Yin Ruixing
- Department of Cardiology, Institute of Cardiovascular Diseases, the First Affiliated Hospital, Guangxi Medical University, Nanning, China
| | - Chen Guangqin
- Department of Cardiology, Institute of Cardiovascular Diseases, the First Affiliated Hospital, Guangxi Medical University, Nanning, China
| | - Wang Yong
- Department of Cardiology, Institute of Cardiovascular Diseases, the First Affiliated Hospital, Guangxi Medical University, Nanning, China
| | - Lin Weixiong
- Department of Molecular Biology, Guangxi Medical Scientific Research Center, Nanning, China
| | - Yang Dezhai
- Department of Molecular Biology, Guangxi Medical Scientific Research Center, Nanning, China
| | - Pan Shangling
- Department of Pathophysiology, School of Premedical Sciences, Guangxi Medical University, Nanning, China
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